Analysis of a national database revealed no new or unexpected safety concerns.

Action Points

Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

PHILADELPHIA -- Over a 10-year period, more than 3,000 U.S. adults who received the measles, mumps, and rubella vaccine (MMR) reported some adverse event following the inoculation, but the number of serious reactions was low, researchers said here.

"No new or unexpected safety concerns after MMR vaccine in adults were observed after reviewing the reports," she told MedPage Today at a poster presentation during the IDWeek meeting.

However, reports indicated that 134 women who were pregnant received the MMR vaccine, which is contraindicated in pregnancy. While Sukumaran's group found that about 60% of those cases involved women who were vaccinated during the first trimester of pregnancy -- in many cases before the patient knew of the pregnancy -- they said the results demonstrated "the need for provider education on [MMR] vaccine recommendations and screening."

Overall, the VAERS reports included nine deaths that occurred from 2 hours to 369 days following administration of the vaccines, she said, but there were no indications that the deaths were directly linked to the vaccine. In eight of nine of the cases, the individuals received other vaccines; seven of the nine individuals who died had pre-existing chronic illnesses.

"One of the problems with [VAERS] is that there is not direct linkage between the vaccination and the report," explained Kathleen Neuzil, MD, MPH, clinical professor of infectious diseases at the University of Washington in Seattle. She explained that if one of the deaths had been caused by an automobile accident after getting a vaccine, it would still be in the report even though the death was not directly related to the vaccine.

Another limitation of the reporting system, Neuzil said, is that it doesn't reveal how many adults received an MMR vaccine.

The CDC recommends that adults born in 1957 or later have documentation of at least one dose of MMR vaccine, and that high-risk adults and healthcare workers have a second dose.

But "limited data exists on the safety of MMR vaccine in adults," the authors pointed.

Sukumaran said that the most commonly reported adverse event was pyrexia (614 cases), but just 40 of those cases was considered serious, she said. About 19% of the reports concerned fevers. The next most frequent complaint was rash, with 502 patients reporting it as a minor event and by 22 people calling it serious.

Sukumaran noted that since 2001, measles cases in U.S. adults averaged less than 100 a year. In 2011, that figure jumped to 200 cases. There were 200 cases reported in 2013, and the provisional number of cases climbed to almost 600 in 2014.

"What we are seeing are outbreaks of measles in adult populations where, for one reason or another, there are groups that are unvaccinated," Neuzil told MedPage Today.

But the low number of reported adverse events offered reassurance "that giving the MMR vaccine to adults did not appear to cause unexpected harm," she said.

Sukumaran received an NIH grant for this research.

She and her co-authors disclosed no relevant relationships with industry.

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